1. Field of the Invention
The field of the invention is adjustable orifice fluid dampers utilized in air and liquid handling systems such as those found in manufacturing and assembly clean rooms, ducts, pipes air handling and fluid flow systems.
2. Description of the Related Art
Fluid flow systems rely on the accurate adjustment of the fluid medium in consideration of static and dynamic conditions. In many cases, dampers are utilized in fluid flow systems for accurate adjustment of the fluid medium.
The prior Patent of one of the co-inventors, namely U.S. Pat. No. 5,218,998, issued Jun. 15, 1993 to the subject co-inventor Gary M. Bakken as well as to inventors Phillip E. Branham and William R. Acorn, and incorporated herein by reference, details an invention of a sliding plate orifice damper system. In such damper systems, the fixed plate has a plurality of specifically arranged trapezoidal shaped apertures therethrough and the slideably adjustable plate overlying the fixed plate also has a plurality of specifically arranged trapezoidal shaped apertures therethrough. The sliding plate is juxtaposed the fixed plate such that the apertures of the sliding plate will overlap apertures of the fixed plate, however, the aperture orientation of the sliding plate is reversed relative the orientation of the apertures of the fixed plate. The result is that the area of the resultant composite hexagonal orifice through both plates varies non-linearly from full open position to full closed position throughout movement of the sliding plate. The functional result is, however, that fluid flow through the resultant orifice from zero to maximum fluid flow is a straight line relationship with linear displacement of the sliding plate (relative to the fixed plate). That being so, dampers comprising this configuration may be preset to pre-determined orifice openings to achieve desired fluid flow results.
While the invention of the above referenced patent achieves the results sought, yet by the construction of the trapezoidal apertures in each of the plates, the volume of fluid which could flow through the damper system is limited from what otherwise might be. After much study and reflection upon the prior invention, it was noticed by the co-inventors of the invention herein that a rather large portion of the area of the two plates did not actually contribute to the resultant hexagon shaped orifice through the overlapping plates. Accordingly, a study was set out to determine how the area devoted to the resultant hexagonal orifices formed of the two plates could be increased so that the ratio of the resultant orifices to the total area of the sliding plate fluid damper might be substantially increased to result in increased fluid flow. Increased fluid flow results in more efficient use of expensive treated fluid, reduced operating costs and equipment costs.
Due to the shape of the trapezoidal apertures it was determined that a substantial part of each aperture in each plate did not contribute to the forming of the resultant hexagonal shaped orifice from complete closure of the orifice to maximum opening. Thus, the task became one of preserving the hexagonal shaped resultant orifice while the plates are moved relative to each other and simultaneously situating more of these orifices on the sliding plate fluid damper system (assuming the size of each orifice does not change). To accomplish such a feat, the apertures on one or both of the plates, i.e., the fixed plate and/or the sliding plate, must be so situated as to be much closer to each other in order to increase the ratio of resultant hexagonal shaped orifice area to the total area of the fluid damper. Obviously this could not be accomplished with the trapezoidal shaped apertures in the two plates since by the very shape of a trapezoid, there must be substantial space between adjacent trapezoids when lined up in rows as shown in the previous patent, space not available to be used for the resultant hexagonal orifice.
Thus, it is readily apparent that it would advantageous in a sliding plate fluid damper system if resultant hexagonal shaped orifices can be maximized by adopting apertures in the fixed plate and/or sliding plate which permit such an increase in the number of hexagonal shaped apertures in the damper system.